1. Field of the Invention
This invention relates to a signal processing device. In particular, it relates to a signal processing device for a medical instrument such as a patient monitoring device.
2. Description of the Prior Art
In various technical fields, signal processing devices are used which comprise a main frame, housing, or cabinet containing electrical circuits, structural elements, etc., and removable modules.
In a prior known signal processing device, a first non-galvanic coupling or area point is provided for each module for transmission of signals from the module to the main device. There is also provided for each module a second non-galvanic coupling point. This coupling point is determined for transmission of signals from the main device to the plug-in module. For transmission of analog information from the modules to the main device, an analog-to-digital converter is mounted before each first coupling point.
Signal processing devices of this kind can be used for various measuring purposes in a great variety of measurement fields. A preferred field of application, however, is electromedicine. Here, a great variety of physiological signals are picked up from the body of a patient and displayed, e.g., on the screen of a cathode ray tube or on the paper of a recorder or on similar display devices. The picked up signals include such different signals as electrocardiogram (EKG) signals, blood pressure signals, respiration signals, CO.sub.2 signals indicating the content of carbon dioxide in the blood or in the respiratory gas, temperature signals, etc.